1. Field of the Invention
The invention relates to a method of testing the piston of an injection pump of a pressure medium, the piston comprising a longitudinal groove on its side, starting from its frontal face, and a screw-shaped guide edge that abuts on the envelope surface of the piston. The invention also relates to a testing apparatus for testing the piston of the injection pump of the pressure medium.
2. Description of the Related Art
The pump element of the injection pump is comprised of a piston and a cylinder, as is well-known. Injection pumps are used for feeding fuel in combustion engines, in particular. The pressures employed are high; therefore, the clearance between the piston and the cylinder is only a few microns. Hence, the tightness and its endurance have an essential impact on the flawless operation of the injection pump.
One problem encountered with injection pumps comprises the cavitation damages in the piston of the injection pump. At first, these generally appear on the envelope surface of the piston, which as such does not affect the operation of the injection pump. Before long, the cavitation damages may also extend to the guide edge of the piston, whereby they have a direct effect on the operation of the injection pump. Such failures due to the cavitation damages and their effect on the operation of the injection pump have previously been difficult to assess and measure.